Composition and process for making fine denier polyamide fiber

Abstract

A composition for making polyamide fiber comprises: (a) about 85 to about 99.9% by weight, preferably about 90 to about 99.5% by weight, more preferably about 95 to about 99.5%, such as about 95 to about 99% by weight of a polyamide, based on the total weight of the composition; (b) about 0.1% to about 15% by weight, preferably about 0.1% to about 10% by weight, more preferably about 0.5% to about 5%, such as about 1 to about 5% by weight of one or more thermoplastic polymers, based on the total weight of the composition, wherein the thermoplastic polymer in the composition is miscible with component (a). A process for making a polyamide fiber uses the composition of the invention.

The invention claimed is: 
     
       1. A composition for making polyamide fiber, comprising:
 (a) about 85 to about 99.9% by weight of a polyamide, based on the total weight of the composition, 
 (b) about 0.1% to about 15% by weight of one or more thermoplastic polymers, based on the total weight of the composition, wherein the thermoplastic polymer in the composition is miscible with component (a); and 
 wherein the thermoplastic polymer is a copolymer of a vinyl aromatic monomer and a (meth)acrylate, and 
 the vinyl aromatic monomer is an non-substituted styrene or styrene substituted with one or more groups selected from the group consisting of methyl, ethyl and propyl; and the alcohol moiety in the (meth)acrylate is derived from C 1 -C 10  alkyl alcohol. 
 
     
     
       2. The composition of  claim 1 , wherein the weight average molecular weight of the thermoplastic polymer is in the range of 1,000 to 20,000. 
     
     
       3. The composition of  claim 1 , wherein the molar ratio of the vinyl aromatic monomer to the (meth)acrylate polymerized into the copolymer is in the range of about 1:100 to about 100:1. 
     
     
       4. The composition of  claim 1  further comprising one or more of an additive comprising: an antioxidant, an antistatic agent, and an UV-absorbing agent. 
     
     
       5. The composition of  claim 4 , wherein the antioxidant is selected from the group consisting of: phosphorus based antioxidants, phenolic antioxidants, sulfur based antioxidants and Antioxidant 163. 
     
     
       6. The composition of  claim 4 , wherein the amount of the additive in the composition is in the range of 0-10 percent by weight, based on the total weight of the composition. 
     
     
       7. A process for making a polyamide fiber, comprising the step of spinning a composition comprising:
 (a) about 85 to about 99.9% by weight of a polyamide, based on the total weight of the composition, 
 (b) about 0.1% to about 15% by weight of one or more thermoplastic polymers, based on the total weight of the composition, wherein the thermoplastic polymer in the composition is miscible with component (a); and wherein the thermoplastic polymer is a copolymer of a vinyl aromatic monomer and a (meth)acrylate; and wherein the vinyl aromatic monomer is an non-substituted styrene or styrene substituted with one or more groups selected from the group consisting of methyl, ethyl and propyl; and the alcohol moiety in the (meth)acrylate is derived from C 1 -C 10  alkyl alcohol. 
 
     
     
       8. The process of  claim 7 , comprising steps of:
 A. obtaining an additive masterbatch comprising the component (b) and the component (a), wherein in the additive masterbatch, the amount of the component (b) is less than 25%, based on the total weight of the additive masterbatch, 
 B. melt-blending the additive masterbatch and additional component (a) to obtain the composition , and 
 C. spinning the composition of step B. 
 
     
     
       9. The process of  claim 8 , wherein before step B, the process further comprises the step of: (A1) drying the additive masterbatch of step A. 
     
     
       10. A polyamide fiber made from the composition defined according to  claim 1 . 
     
     
       11. The process of  claim 7  comprising a high shear rate during the process, with the shear rate being at least 2000 s − . 
     
     
       12. An article, prepared from the polyamide fiber of  claim 10 . 
     
     
       13. A blend, comprising the polyamide fiber of  claim 10 . 
     
     
       14. The polyamide fiber of  claim 10  comprising a having a linear density in the range of from 0.3 to 0.8 dtex and a tensile strength in the range of from 2.7 to 3.6 cN/dtex.